The problem with single mode is you can't get much power out of them for R,G or Blue (after normal lens losses) unless pushing them far beyond their ratings, blue giving the most at over 250mw, green maybe 120mw if pushed hard, I don't remember what I was able to get out of a red single mode but I don't think much over 175mw, I suppose I could have pushed the diode harder for more power but one member told me the output can depart from a normal single mode profile if pushed too hard. If you do go for red, I recommend 638nm as it is brighter to the human eye than 650nm.
Search ebay for single mode diodes and you will see some ratings, nothing actually rated at 200-300mw, most much lower. The low divergence of these single mode diodes is great for putting a dim spot on a high cloud base at night, but not very impressive compared to a multimode diode running a watt or more IF used with a beam expander. I recommend getting a higher power multimode laser diode and putting a 10X expander on it to make them have lower divergence. That way, you have a bright beam and low divergence at the same time, although a fat beam which makes it look dimmer due to being fatter, still far more brilliant than a single mode laser diode.
Edit: As usual, always an edit, why should this post be any different? One thing to watch out for if putting an expander on a multimode laser diode is that its input lens is big enough to accept the beam, some beam expanders have very small input apertures and multimode diodes normally have large diameter outputs. I've been buying some surplus Linos beam expanders, they have a nice wide input and can be adjusted from 2 to 8X, so if you don't want such a fat beam, you can turn it down.
Here's a Linos beam expander which can be used for red on ebay, this guy has been taking 100 dollars each if you offer it:
Linos Laserbeam Expander 2 8x 630 830nm | eBay This same seller has some beam expanders of the same kind which will work for green. You might think 100 dollars is a lot of money for one, but new they are over 1500 dollars each. Take this same beam expander and couple it with a single mode diode for even less divergence, then you would have uber low divergence, but since the beam would be fatter, less power density and even less impressive when viewed from the side.
For myself, for your first single mode, if you do go for that, I'd get a green single mode, due to the sensitivity of the eye being so much higher for green than red and blue, it's 10 times brighter at the same power level. A 50-100mw red single mode diode has a fairly dim beam when viewed from the side and blue is not much different.
:beer: